Added suport to configurable application model

Conflicts:
	oauth2_provider/models.py
	oauth2_provider/settings.py
Fixed docstrings
using get_application_model
Close issue #31. Add DocString to exception classes
Restyling DocString
REST framework integration tutorial updated: removed ScopedResourceMixin which is no more necessary
Changelog updated
save user in request.resource_owner (solution by @ib-lundgren)
function based views support - first draft
fixed error msg
pep8 fix
added tests for decorators
better tests
run tests for decorators
removed tutorial 03
removed foo application
Use contrib.auth user model in tests
compat module simplified
Removed django_coverage dependency
Spelling fix, followin => following